1. Field of the Invention
The present invention relates to timing controllers mounted in image display devices such as liquid crystal display devices and, more particularly, to a technique for recognizing the resolution of a display panel.
2. Description of the Background Art
To a liquid crystal display device, for example, signals which are references for controlling the driving circuits in the liquid crystal display panel (hereinafter, referred to as “control reference signals”), clock signals which are references for the timings of operations and the like are input from the outside of the device, along with image data. The aforementioned control reference signals include a horizontal synchronization signal for synchronization in the horizontal direction of the liquid crystal display panel, a vertical synchronization signal for synchronization in the vertical direction of the liquid crystal display panel, a data enable signal indicative of the time period during which image data is effective, and the like. The image data and these control reference signals are input to a control circuit called a timing controller which is mounted in the liquid crystal display device.
The timing controller creates control signals for controlling the display panel driving circuits, based on the control reference signals, and transmits the control signals to the driving circuits, along with the image data. The driving circuits drive the liquid crystal display panel according to the control signals and the image data to cause it to display images (refer to Japanese Patent Application Laid-Open No. 2004-45985, for example).
The timing controller is required to correctly recognize the resolution of the liquid crystal display panel, in order to create proper control signals. In conventional liquid crystal display devices, information about the resolution to be recognized by the timing controller has been held as an invariable in advance in the timing controller or stored in a memory in the timing controller. However, in this case, the addressable resolutions are restricted by the respective timing controller.
Further, the timing controller may determine, by itself, the resolution of the liquid crystal display panel based on the length and the number of the data enable signals included in the control reference signals and may recognize it. However, various types of control reference signals are input to the timing controller, depending on the specification (design policy) of the scaler or the like for creating the control reference signals and, accordingly, control reference signals can not be adapted to all timing controllers. In the event that control reference signals which do not match (mismatch) with the specification of the timing controller are input to the timing controller, the timing controller can not be expected to create proper control signals. Accordingly, there may be cases where the liquid crystal display device incorporating the timing controller can not be combined with the device incorporating the scaler, depending on the correspondence between the timing controller and the scaler.
Also, if the timing controller is designed in consideration of mismatch with control reference signals, this will complicate the circuit structure of the timing controller, thereby inducing problems such as an increase of the fabrication cost.